The Finnish Diabetes Prevention Study (DPS) published in 2003 was remarkable, demonstrating that diet and physical activity measures alone could reduce the cumulative incidence of diabetes in individuals with impaired glucose tolerance (IGT) by 58% (summarised to the right). The long-term follow-up study has equally remarkable findings (Lindström et al, 2013).
The original study randomised 522 overweight or obese subjects with IGT to lifestyle intervention or control. The intervention group received a degree of input not unrealistic in a structured primary care setting: goals of reduction in weight by 5%, reduced fat intake and moderate exercise for ≥30 minutes per day. Carbohydrate intake included wholemeal products, vegetables, berries and fruit, alongside high-protein foods. Subjects had seven sessions with a nutritionist during year 1 and every 3 months thereafter, plus individual guidance on increasing physical activity. By the end of year 1, subjects in the intervention group lost an average of 4.2 kg, but gradually returned close to baseline weight during and after the study – a reminder that degree of weight loss need not be huge in order to induce major health benefits. The recent paper is reminiscent of the UK Prospective Diabetes Study (UKPDS) “legacy” paper (Holman et al, 2008).
After the DPS ended (prematurely, due to early success), levels of physical activity between the two groups equalised, and the degree of dietary change between the groups diminished, yet the difference in cumulative incidence of diabetes remained. To quote the authors: “our findings suggest that lifestyle intervention lasting for a median of 4 years can result in long-term protection against type 2 diabetes”. A statistically significant difference in body weight between the two groups persisted at 10 years. There was a 32% relative risk reduction, and a 15% absolute risk reduction for a diagnosis of diabetes during the post-intervention follow-up period in favour of the intervention group. The number needed to treat to avoid one case of diabetes was 5.2.
Like UKPDS, this shows that prompt, responsible treatment of people with poor glycaemic control has beneficial outcomes years later, even when the intensive treatment is for a short time. Unlike the UKPDS paper, however, which studied newly diagnosed, drug-naïve individuals with diabetes, this paper looks at older, higher-risk patients, for whom a delay or avoidance of diabetes makes a big difference to their onset of complications and life-expectancy.
It is clear from these studies that diet and lifestyle advice, rather than being a detail to dismissively gloss over in the final few seconds of a consultation, are cornerstones of management of diabetes and obesity.
To view the summaries of each paper, please download the PDF.
